A DAC and its connected power and input signal components require ultra-low noise for best sound. This cannot be overstated.
For DACs with a DC input:
Replace the factory provided (external brick) switch-mode supply with a compatible 3rd party linear PSU with better regulation and filtering. Look for power supplies with upgraded fuses or improved wiring to further add benefit of additional RF filtering.
For best performance, use a battery to avoid galvanic contact with AC mains and other AC connected components. Consider LiFePO₄ (LFP) technology for the lowest electrochemical discharge noise and low EMI BMS (battery management system) such as 'DALY' brand.
Avoid buck-type voltage regulators or integrated digital logic modules in the battery or power supply; these only add RF noise.
RF•STOP™ DC Power Filter is a two-stage design that uses inductors of highly permeable core material for excellent attenuation of common-mode and normal-mode noise up to the critical RF frequency of 500MHz. A maximum current rating of 4A ensure sufficient performance for most DACs.
Normally RF•STOP is located between the power source and DC input to a component, however RF•STOP can also be used to isolate components that are powered by the same DC power source (via a splitter cable). Installing RF•STOP between two component prevents transfer of RF noise between them. Additionally RF•STOP may be used to ensure that a galvanic digital signal input (dual coax) from OPTO•DX or source is properly filtered.
Use 2.1mm or 2.5mm connections for input and output and a well shielded DC power cable such as Gotham GAC-4/1 11301 UltraPro Star Quad. Avoid long cable runs to minimize EMF induced noise via antenna effects; ideally locate RF•STOP close to the component and use ultra-short cables (0.3 meter or 12 inches).